Hard to start after a few days?

[sail_flathead_lake]

Hi all,

My new-to-me Tartan 27 has an issue that my other A4 never had: If the engine sits for a few days, it becomes hard to start. When this happens, it sounds like it's not getting fuel. I have to crank it for several (5 - 10) ten second tries before it will start to sound like it's getting fuel, and then once it catches it runs great. If I've started it the day before, it starts right up, first try.

It's not a spark issue as when this happens I've checked spark and found a healthy spark. Is it possible that the fuel in the bowl is leaking out over the several days that the boat sits? The fuel pump is electric, with OPSS, and there is a fuel filter (spin off type) on the line. Full disclosure - the gas is a couple of years old, but as I mentioned, it runs like a champ once it starts. Also, it always starts right away if I ran the motor the day before. It's only after sitting for a few days that it gets hard to start. Yes - I do close the raw water intake when cranking under those conditions.

Thanks!!!

[JOHN COOKSON]

I've noticed this phenomenon too. The longer the time since the last start the more difficult it is to start.
I always attributed it to the fact that I have the idle set as lean as possible.
Maybe I should check the timing sometime? Or what???

TRUE GRIT

[BunnyPlanet169]

Thinking out loud, I can imagine two possible causes, but this is not from hard experience.

First, it's plausible that some longer duration off time, the carb takes longer to get 'wet'. Fuel should be in the bowl, but maybe it does evaporate slowly? Fuel lines may or may not drain back to tank, etc. Choke adjustment could come into play.

A second thought is that with an OPSS, after an extended off period, it may take longer for oil to fill and pressurize in the oil galleys. This would tend to amplify the first scenario....

??

[JOHN COOKSON]

Don't think it has anything to do with the OPSS. The carb bowel should be full of fuel from the last run and give ~45 seconds of run time even if the OPSS is not functioning at all.

Maybe has to do with updraft carbs? Dave N. are you logged on?

TRUE GRIT

[Mo]

Very small diaphragm leak in a manual fuel pump or a very small leak at a joint such as fuel filter, fuel filter seal etc. My guess would be a pump leak allowing a little air in...very common with diesel engines. Generally a sign of the pump on the way out.

[Dave Neptune]

As the engine sits some of the fuel will evaporate, a bunch at first due to the heat in the engine dissipating and will continue when the engine cools. An updraft carb is far more susceptible to lean starting causing longer cranking times. This is a good thing as it allows for the oil pump to get some oil where it needs to be before igniting into life.

Yes a really lean idle will take longer and that to is still a good thing.

The fuel lines draining back and or the "OPSS" needing a few more spins to "close" will also add time for the "start". I consider this all good. Many "hot rods" with really powerful engines have a start switch and ignition switch to do the same thing. Some engine we'll crank for 15~20 seconds before hitting the ignition switch~this just to be sure oil is in the right places~a good thing!

Any time I hear someone mention that there A-4 instantly starts I think the idle is way to rich or the floats are way to "high", and wait to hear of plug fouling. Any engine with an updraft carb (no acceleration pump) SHOULD take a few more turns to get fuel into the combustion chambers to get it lit!

Dave Neptune

[edwardc]

I had a Honda Civic that did the exact same thing. Would start fine if run daily, but a hard start if left over a weekend. Problem turned out to be sticking valves. The cure (which took some time) was to add MMO to the oil. I went pretty heavy and replaced a full quart of the oil with MMO.

[Skywalker]

Dave, well I'm that guy with the A4 that starts right up. She even fired up within a couple of seconds after being winterized and then sat for 7 months. Guess I'm a little rich!

Something else to add to the list.

Chris

[capnward]

Hi Flathead Lake Sailor, with a Flathead engine,

Since your engine runs fine once it starts, there's probably not much water in the gas, or crud restricting the fuel line or carburetor orifices/jets, or a problem with the fuel pump. Although, I have a mechanical pump, so I don't know about OPSS. I suspect the timing, or the fuel/air mixture being too lean, or the choke adjustment as the likely culprits. Having a fuel pressure gauge in the line just before the carb could tell you if you have a leak in the fuel line, if the needle drops after the line is pressurized. That and wet hoses. (Shudder) Be vigilant! Always sniff for gas. Good Luck.